Transmission Info

[..SSR..]

Ah, gears. So many people screw this stuff up.

 

Numerically low gearing is referred to as high geared.

Numerically high gearing is referred to as low geared.

 

A final drive is actually two parts. A ring gear (which bolts onto your differential), and the countershaft (which your counter gears are mounted onto). Don't be confused by what people tell you. It does now give you close gearing, close ratio, short gearing, etc. It does not affect your gears at all. What it does is get you through each gear quicker (FD:1-3 :: gears:1-7 assuming you have a 21 speed bicycle). It does not change the RPM drop between gears, but you will be at a higher RPM in every gear, which will also reduce your top speed (unless you put in a numberically lower gear which will get you through each gear slower and raise your top speed).

 

Gears are just that, gears. Each gear (1-2-3-4-5-6-R) is actually two gears. A main and counter gear, referred to as a gearset. Honda's do not have interchangable 1 and 2 (though aftermarket companies have now developed a longer 1 for B series hydro transmissions, which consists of only one gear versus a gearset). 1 and 2 are built into the mainshaft, while the 1 and 2 counter gears slide onto the countershaft. 3-4-5-6 are interchangable for most Hondas. Gears will get you through the gears faster as dumb as that sounds. A numerically higher gear will lower your RPM drop going into the next gear, get you to your shift point faster (getting through the gear faster, but didn't want to confuse anyone), as well as lower your top speed. A numberically lower gear will do the opposite. The benefit of numerically lowers gears are that you stay in the powerband when shifting into the next gear (most aftermarket close gearsets will give you change your RPM drop going from 2-3 to 1,500-1,600, increasing about 100 RPM for every gear after).

 

The downside to FD's and gears is traction. If you have a lot of power (F/I, big N/A builds) you will probably spin each gear versus barking them like you would with a stock transmission. N/A this isn't a problem. F/I you have a lot more torque and will just keep spinning in each gear not gaining much speed. So for a big power F/I build, you would either want a stock gear trans with a numerically higher final drive or a close geared trans with a numerically lower final drive.

 

Tire size also plays into gearing. A basic rule of thumb is that a 20" OD tire is about the same as a 4.9 final drive. I've never tested this though or played with it in gearing calculators. A smaller OD tire will be the same as putting in a numerically higher final drive. A larger OD tire will be the same as putting in a numerically lower final drive. The good thing about this is you can use tire sizes to somewhat control your cruising speed. Do a lot of highway driving but want a final drive or close gears? Get an extra set of wheels to daily drive with and use a large OD tire.

 

Differentials

These are a whole other box of tricks kind of. Most Hondas come with open differentials (look into it and you can't see through). This means that only one wheel gets power (one wheel peel). Sure you might smoke both tires when burning out, but that doesn't mean you have an LSD... A limited slip differential (look into it and you can see through it) gives both wheels power (the one that slips gets the grip). LSD also helps improve your handling, but thats another subject.

 

Cable and hyrdo

This is the type of transmission you have. Hydro (hydrualic) trannys use fluid (brake fluid) to disenage the clutch. The fluid is in a clutch line between the clutch master cylinder and the clutch slave cylinder. The slave cylinder is bolted onto the transmission and is what pushes the clutch fork to disengage the clutch. Cable trannys are simpler. They use a cable to disengage the clutch. Rather simple so use your imagination.

 

Interchangability

Gears, FD's, diffs, etc are not interchangable between series (only exception being a B16 diff in a D16A1 trans). If it is the same series (D-D, B-B, F-F, etc) then they will interchange (cable and hydro usually will not). B series you can put hydro gears into cable trans (ex. B16 gears into certain cable Integra trannys). D series you cannot do this...yet. D series though most 3-4-5 gears can be interchanged for each other, and 3rd gear can even be used as 4th gear.

 

Converting

Have a D series 4-spd and want 5? Or a K series 5-spd and want 6? No problem. 4/5 and 5/6 speed trannys are the same. The only reason you don't have the extra gear is the gearset is missing (either 5 or 6) along with the shift fork being different (and a few minor other things). Gearsets missing? Instead of putting the gearset in, Honda instead put spacers in. These are just metal sleeves more or less.

 

Notes: To find out what ratio your gearset is, you need to count the teeth on each gear. Then divide the two and that will give you the ratio (ex. 1.033). For final drives, count the teeth on the ring gear as well as the countershaft and divide.

[cranny]

i think ive covered most of that , lol. couple times.

[TS John]

That's a nice post, man. Always good to have all the info in one place.

 

Quick question: when you say that it's not a problem to go up from a 4 to 5 speed etc., would that require a different clutch as well? I'm assuming yes, but you made it sound so simple that I might as well ask. I certainly wouldn't mind going up to a six speed in my sol but I don't want to have to rebuy the clutch setup I'm about to get.

[cranny]

you cant turn your 5 spd D or B tranny into a 6. the shafts are only so long. you guys see the new 8 spd auto? forget what it comes in. BMW i think.